I debricked my black Kindle 4NT with the firmware version 4.1 but because there was no diags images for firmware 4.1 I flashed the mmcblk0p2-4.0.0 and restored my Kindle by using the mmcblk0p1-4.1.0 via SSH.
No my Kindle boots and sohow all available wifi networks, but if I try to connect the conection fails.
update:
It works after setting date via SSH and ignor the wifi error message.